WASHINGTON— As carbon levels in the atmosphere approach 400 parts per million, a new study finds that global warming, left unchecked, will cause major declines of more than half of the world’s plants and a third of animals by 2080. The study, published in the journal Nature Climate Change, found that by 2080 global warming will make more than half of the existing habitat for 6 out of 10 plants uninhabitable and do the same for about a third of animal species. However, the study notes that immediate and strong action to reduce emissions could cut these losses by 60 percent.

Photo of polar bears courtesy USFWS. Photos are available for media use.

“The terrifying loss of biodiversity predicted by this study shows that climate chaos will fundamentally transform our planet,” said Shaye Wolf, climate science director at the Center for Biological Diversity. “But President Obama and other leaders can still save plants and animals by getting serious about fighting carbon pollution. We need to cut emissions now, before our ecosystems suffer catastrophic damage.”

The new study was published within days of news that carbon dioxide in the atmosphere is, for the first time in millions of years, approaching 400 parts per million. The milestone hasn’t actually been surpassed yet, according to a revised reading of data collected by instruments in Hawaii. But the milestone will likely be hit and surpassed in the coming weeks — a clear sign that greenhouse gas pollution from power plants, cars and other human sources continues on a troubling upward trajectory. Scientists have warned for years that CO2 levels in the atmosphere must be reduced to 350 parts per million to avoid catastrophic climate change.

Over the past year, the signs of climate change have been unmistakable, including Superstorm Sandy, thousands of shattered heat records, deadly heat waves, historic drought, food shortages and record low sea ice across the Arctic. In recent years climate change has dramatically worsened conditions for species around the globe, many of which were already imperiled, including polar bears, wolverines, American pikas and dozens of fishes and corals.

“Alarm bells are going off all around the world that our climate is moving in a very dangerous direction,” Wolf said. “Ignoring these signs isn’t just irresponsible, it’s immoral.”

Both the technology and the legal tools to achieve rapid greenhouse pollution reductions are already in place. Full use of all of the Clean Air Act’s successful pollution-reduction programs is our best route to quick reductions in greenhouse gas emissions. The Obama administration, however, has been too slow and timid in using the law to cut pollution. In response more than 50 cities, including Los Angeles and Miami, have joined the Center’s Clean Air Cities campaign, which urges President Obama and the EPA to address the climate crisis through the Clean Air Act’s science-based programs.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 500,000 members and online activists dedicated to the protection of endangered species and wild places.